1. Field of the Invention
The present invention relates to a branch image pickup and view system having an optical image pickup system and a view finder system, for use with a CCD camera, such as a small video camera, a digital camera or an electronic still camera, etc.
2. Description of the Related Art
In recent CCD cameras, the picture plane size of the CCD as a light receiving element is reduced from 1/2" or 1/3" to 1/4" or 1/5". Attempts have also been made to miniaturize CCD cameras. Moreover, the conventional CCD camera is usually provided with a liquid crystal (LC) finder and/or an optical view finder as a means for visually confirming images to be picked up. There are various types of optical view finders, such as a view finder independent from the optical image pickup system or a branch view finder bifurcated therefrom.
The LC finder has drawbacks such as that it consumes a large amount of electrical power, thus resulting in reduced service life of a battery to be used; the movement of the images displayed in the picture plane is discontinuous, and the resolution is lower than that of the optical. view finder.
In an optical view finder independent from the optical image pickup system, there is a difference (parallax) for an object which is located at an object distance other than a specific or reference object distance, between the photographing range of the image pickup system and the view range of the view finder.
The branch view finder bifurcated from the image pickup system has no parallax but has drawbacks such as that it is difficult to meet the requirements of miniaturization and ease of viewing through the finder. If the picture plane size of the image pickup system (CCD) is reduced to miniaturize the view finder, the picture plane size of the primary image forming surface is also reduced in the bifurcated light path of the optical view finder, and an apparent emission angle (angle of view) becomes small, so that the image to be viewed is made small, thus resulting in difficulty in observation through the finder.
If the focal length of the eyepiece is reduced to increase the apparent field of view, pupil diameter and eye relief are reduced, and hence a vignetting tends to occur even due to a slight movement of the eye, so that a clear image cannot be viewed through the view finder.